NexGard Size Guide for Dogs | Weight Chart, kg ↔ lb Conversions & Buying Help

Choosing the correct NexGard size is one of the most important steps in giving your dog safe, effective flea and tick protection. NexGard chewables are dosed by your dog’s current body weight, and every pack is colour-coded and clearly labelled with a weight range printed in kilograms (kg). If you grew up with pounds (lb) — or you’re shopping from the US, UK or anywhere else that uses imperial — the charts on this page give you side-by-side kg ↔ lb conversions so you can pick the right pack with confidence.

This guide goes beyond a simple chart. We’ll walk through how NexGard sizing actually works, how to weigh your dog accurately at home, what to do if your dog is sitting right on a weight boundary, how the active ingredient kills fleas and ticks, sensible dosing rules, what to do if you miss a dose, the safety information you should know, plus storage, handling and tips for buying genuine product. If you only want the chart, jump straight to the NexGard weight chart.

How NexGard sizing works

NexGard sizes are based entirely on weight — not breed, age or coat type. Each colour-coded pack matches a specific weight band, and the dose of the active ingredient (afoxolaner) inside the chew is calibrated to that band. A 5 kg Cavalier King Charles Spaniel and a 5 kg Miniature Schnauzer take exactly the same NexGard, even though they look nothing alike, because their bodyweight is the same.

To choose the right pack:

• Weigh your dog as accurately as possible — ideally within the last week or two.
• Select the colour/size that matches your dog’s current weight on the label.
• Use one size category per dog — never combine smaller chews to make up a bigger dose.
• Always follow the label directions printed on the packaging.
• If your dog gains or loses weight, review their size again before your next reorder.

NexGard weight chart (kg + lb)

Use the chart below to choose the correct NexGard size based on your dog’s current bodyweight. Pound values are rounded to the nearest whole number to match the labels printed on US-sized packs.

Browse the full range: 👉 Shop NexGard for Dogs

Quick kg ↔ lb reference chart

Common dog weights with kg, lb, and the correct NexGard size at a glance.

How to convert kg to lb (with examples)

The exact conversion is straightforward, and it’s worth knowing if your scales only show one unit:

• lb = kg × 2.2046
• kg = lb ÷ 2.2046

For most NexGard sizing decisions, you can round to 2.2 in your head and still land in the right colour band. Some quick mental cues:

• 1 kg ≈ 2.2 lb
• 5 kg ≈ 11 lb
• 10 kg ≈ 22 lb
• 25 kg ≈ 55 lb
• 50 kg ≈ 110 lb

Worked examples:

• “My dog is 18 lb — what kg is that?”  18 ÷ 2.2046 = 8.16 kg → Blue (Small).
• “My dog is 32 kg — what lb is that?”  32 × 2.2046 = 70.5 lb → Red (Large).
• “My dog is 11 kg — she’s right on the line”  11 × 2.2046 = 24.25 lb → Green (Medium). Always size to the colour the printed pack range covers.

How to weigh your dog accurately at home

Guessing weight is the single biggest source of sizing mistakes. A dog that looks “about 10 kg” can easily be 8 kg or 12 kg — which can push them into a different NexGard band. Here’s how to get an accurate number without a vet visit:

1. Small dogs (under ~15 kg / 33 lb): Step on your bathroom scales alone, note the number, then pick up your dog and weigh again. Subtract the first number from the second.
2. Medium and large dogs: Most vet clinics, pet stores and dog groomers have a flat platform scale and will let you weigh your dog free of charge — you don’t need an appointment.
3. Be consistent: Weigh in the morning, before a big meal, and ideally without their collar/harness so the number reflects the dog, not the gear.
4. Puppies: Re-weigh every 4–6 weeks while they’re growing. Puppies can move through two NexGard size bands in just a few months.

If your dog is on a size boundary

Some dogs sit awkwardly between two NexGard ranges — for example, a 10.8 kg Beagle (just inside Blue) or an 11.2 kg one (just into Green). The general principles are:

• Always size up, not down. If your dog is genuinely on the boundary, the larger pack provides a sufficient dose; the smaller pack may underdose.
• Never split or combine chews. NexGard chewables are not designed to be cut in half — the active ingredient may not be evenly distributed, and the chew is intended to be eaten whole.
• Don’t use two small chews instead of one large. The dose is calibrated to single-chew administration. Stacking sizes is not equivalent and is not recommended.
• Talk to your vet. For dogs at the very top or bottom of a band, especially if they’re still growing or losing condition, your vet can confirm the right pack.

How NexGard works — afoxolaner explained

NexGard’s active ingredient is afoxolaner, a member of the isoxazoline class of parasiticides. Once your dog chews and swallows the beef-flavoured tablet, afoxolaner is absorbed quickly into the bloodstream from the gut.

When a flea bites your dog, or a tick attaches and starts feeding, the parasite ingests afoxolaner along with the blood meal. Afoxolaner targets specific GABA- and glutamate-gated chloride channels in insect and arachnid nervous systems — receptors that are very different from those in mammals — causing uncontrolled neural activity, paralysis and death of the parasite. Mammalian receptors are not meaningfully affected at therapeutic doses, which is why the product has a wide safety margin in dogs.

Practical timing you can expect:

• Fleas: NexGard begins killing fleas within roughly 30 minutes of being eaten and achieves full kill within about 8 hours — for the entire 30-day period.
• Ticks: Most species (paralysis tick, brown dog tick, bush tick) are killed within roughly 24–48 hours of attachment.
• Duration: One chew gives 30 days of protection. NexGard is dosed monthly.

Because afoxolaner works systemically (through the bloodstream rather than on the coat), bathing, swimming, towel-drying or rolling in the dirt does not reduce its effectiveness. There’s also no greasy spot-on residue and nothing for children or other pets to contact.

Dosing schedule & missed-dose guidance

The basic schedule

• Frequency: One chew every 30 days, year-round in most climates.
• Minimum age: NexGard is approved for puppies from 8 weeks of age, provided they weigh at least 1.8 kg / 4 lb.
• With or without food: NexGard can be given with or without a meal. Some owners find it easier to give just before mealtime so the chew is taken eagerly.
• Make sure it’s eaten: Watch your dog actually swallow the chew. If it’s spat out or only partially eaten, the dose may be insufficient.

If you miss a dose

• If you’re only a few days late: Give the missed dose as soon as you remember and shift the calendar forward so the next dose is 30 days later. Protection resumes quickly once the chew is eaten.
• If you’re weeks or months late: Give a dose immediately and resume monthly dosing from that date. Talk to your vet about whether your dog should be checked for fleas, flea allergy dermatitis or tick-borne disease, especially if you live in a paralysis-tick area.
• If your dog vomits within 2 hours of eating the chew: Re-dose with a fresh chew of the same size. After 2 hours absorption is generally complete and re-dosing isn’t needed.

Safety, side effects & vet warnings

NexGard has been used safely in millions of dogs since its introduction in 2013, but no flea and tick treatment is completely free of side effects. The information below is a general summary — always read the leaflet inside your pack and follow your veterinarian’s advice.

Reported side effects

The most commonly reported side effects in clinical studies were mild and self-limiting:

• Vomiting
• Itching, dry or flaky skin
• Diarrhoea
• Lethargy
• Loss of appetite

Most resolve without treatment. If they persist for more than 24–48 hours, or if they’re severe, contact your vet.

Isoxazoline class warning

In 2018 the US FDA issued a class-wide alert noting that isoxazoline-class products (including NexGard, Bravecto, Simparica and Credelio) have been associated in rare cases with neurological reactions — muscle tremors, ataxia (wobbliness) and seizures — even in dogs with no prior history. The reactions are uncommon and most dogs tolerate the medication without issue, but you should:

• Tell your vet if your dog has a history of seizures or neurological disease before starting NexGard.
• Stop the medication and contact your vet immediately if your dog develops tremors, unsteadiness or a seizure after a dose.

When to call your vet

Use during pregnancy, lactation and breeding

NexGard has been evaluated for use in breeding, pregnant and lactating dogs and is generally considered safe in these animals, but always confirm with your vet before dosing a pregnant or lactating bitch.

Storage, handling & buying genuine product

Storage

• Store NexGard in its original packaging at room temperature — ideally below 30°C / 86°F — out of direct sunlight.
• Keep chews out of reach of children and other pets. NexGard is highly palatable and a curious dog or toddler may try to eat several at once.
• Do not use after the printed expiry date. An expired chew may not provide full protection.

Handling

• Wash your hands after handling the chew, especially before eating.
• If you’re giving it directly from your hand, give it as a single piece — don’t cut it.
• If your dog drops it and a different pet picks it up, that other animal has effectively had the dose — redose your intended dog with a fresh chew and contact your vet if the “wrong” pet is a cat, very small dog or species the chew isn’t indicated for.

How to make sure you’re buying genuine NexGard

Counterfeit and grey-import flea/tick chews appear from time to time on auction sites and unfamiliar online stores. To stay safe:

• Buy from established retailers that source product from authorised wholesalers.
• Check the packaging is sealed, the batch number and expiry date are printed clearly, and the colour-coded labelling matches the official sizing.
• Avoid loose chews sold individually outside their original blister packs — you can’t verify storage history or authenticity.
• If a price looks dramatically lower than every other store, treat that as a warning sign rather than a bargain.

At Smartway Pet Supplies we stock 100% genuine NexGard, shipped worldwide from Melbourne, Australia, with secure encrypted checkout and free standard shipping on orders over $125.

Frequently asked questions

Can I give two smaller NexGard chews instead of one larger one?

No. NexGard is dosed as a single chew per month based on weight band. Combining two smaller chews is not equivalent to one larger chew and is not recommended by the manufacturer.

What if my dog spits the chew out?

If your dog refuses or spits it out, try offering it inside a small piece of cheese, peanut butter or their normal food. The chew is beef-flavoured and most dogs eat it readily, but a small minority need a little encouragement.

Can I give NexGard with heartworm or other medications?

NexGard covers fleas and ticks but does not cover heartworm or intestinal worms. Many owners pair NexGard with a separate heartworm/wormer, or use NexGard Spectra, which combines afoxolaner with milbemycin oxime to cover fleas, ticks, heartworm and intestinal worms in one chew. Always check with your vet before combining medications.

How is NexGard different from NexGard Spectra?

NexGard handles fleas and ticks only. NexGard Spectra adds protection against heartworm and intestinal worms (roundworm, hookworm and whipworm). The size bands and colour coding differ slightly between the two products, so always size based on the specific product you’re using.

How young can puppies start NexGard?

From 8 weeks of age and at least 1.8 kg / 4 lb bodyweight. Re-check sizing every 4–6 weeks during rapid growth.

Can NexGard be used in cats?

No. NexGard chewables are formulated and dosed for dogs only. For feline flea and tick protection see cat-specific products such as Bravecto for Cats or Revolution Plus.

Does swimming or bathing affect NexGard?

No. Because afoxolaner works systemically through the bloodstream, water exposure, swimming, shampoo and rain do not reduce its effectiveness.

Is a prescription required?

Requirements vary by country. In Australia NexGard is available without a prescription. In the US it is a prescription product through your vet. Check your local rules before ordering.

When to review your dog’s NexGard size

Sizing isn’t a once-and-done decision. Re-check the colour band you’re ordering:

• Whenever your dog gains or loses noticeable weight — for example after de-sexing, dietary changes or illness.
• As puppies grow and move into new weight categories.
• When you start a new annual routine or set up a subscription reorder.
• If your dog has been on a weight-loss program recommended by your vet.
• If you’re unsure — weigh, then check the chart again. It only takes a minute.

Selecting the correct size is the most important step in making sure NexGard works the way it should. Once you’ve chosen the right colour band you can browse the full range here:

👉 Shop all NexGard chewables at Smartway Pet Supplies